Drill string flow control valves and methods

A drill string flow control valve comprising:

• a valve housing, wherein the valve housing is characterized by a cylindrical wall extending from a first end to a second end and defining a valve interior, wherein the valve housing has an internal housing flow path channel formed between said first and second ends with a housing outlet flow port disposed along said flow path channel;
• a valve sleeve disposed at least partially in the valve housing, the valve sleeve characterized by a valve sleeve wall having a sleeve flow port defined therein, wherein the valve sleeve is axially movable within the valve housing between a closed position and an open position, such that fluid flow between said housing outlet flow port and said sleeve flow port is substantially impeded when the valve sleeve is in the closed position and wherein the sleeve flow port and the housing outlet flow port are substantially aligned when in the open position;
• wherein the valve sleeve has a first pressure surface defined thereon so as to provide a first surface area upon which a first fluid pressure from the housing flow path channel may act to provide a downward force on the valve sleeve, and wherein the valve sleeve has a second pressure surface defined thereon so as to provide a second surface area upon which a second fluid pressure may act to provide an upward force on the valve sleeve;
• a biasing mechanism wherein the biasing mechanism biases the valve sleeve to the closed position;
• a first pressure channel split off from said internal housing flow path channel, said first pressure channel disposed to allow the first fluid pressure to act upon the first pressure surface;
• a second pressure channel that allows the second fluid pressure to act upon the second pressure surface from external the valve housing;
• an elongated piston having a first end and a second end and axially movable within the valve housing, wherein the second end of the piston is disposed to bear against the valve sleeve and wherein the first end of the piston has a piston pressure surface characterized by a piston surface area;
• and
• a piston pressure port split off from said internal housing flow path that allows a fluid pressure internal to the valve to act upon the piston pressure surface.

A method for preventing u-tubing in a drill string comprising:

• providing a valve housing, wherein the valve housing is characterized by a tubular wall extending from a first end to a second end and defining a valve interior, wherein the valve housing has an internal housing flow path formed between said first and second ends with a housing outlet flow port disposed along said internal flow path;
• providing a valve sleeve disposed at least partially in the valve housing, the valve sleeve having a sleeve flow port and a valve sleeve wall, wherein the valve sleeve is axially movable within the valve housing between a closed position and an open position, such that fluid flow between said housing outlet flow port and said sleeve flow port is substantially impeded when the valve sleeve is in the closed position and wherein the sleeve flow port and the housing outlet flow port are substantially aligned when in the open position, wherein the valve sleeve has an upper pressure surface defined thereon so as to provide a first surface area upon which a first fluid pressure may act to provide a downward force on the valve sleeve and wherein the valve sleeve has a lower pressure surface defined thereon so as to provide a second surface area upon which a second fluid pressure may act to provide an upward force on the valve sleeve;
• providing a biasing mechanism wherein the biasing mechanism biases the valve sleeve to the closed position by exerting a biasing spring force on the valve sleeve;
• providing an upper pressure port split off from said internal housing flow path, said upper pressure port disposed to allow the first fluid pressure to act upon the upper pressure surface from the internal housing flow path with a first force;
• providing a lower pressure port that allows the second fluid pressure to act upon the lower pressure surface from external the valve housing with a second force;
• providing an elongated piston having a first end and a second end and axially movable within the valve housing, said first end of the piston having a piston pressure surface and said second end of the piston bearing against the valve sleeve;
• providing a piston pressure port split off from said internal housing flow path and that allows a fluid pressure internal to the valve to act upon the piston pressure surface;
• introducing drilling fluid into the valve to induce a fluid pressure to be applied to the piston pressure surface via the piston pressure port, thereby causing said piston to urge the valve sleeve from a closed position;
• increasing the fluid pressure upon the valve sleeve so as to cause the valve sleeve to axially move against the biasing direction of the spring, thereby increasing fluid flow through the housing outlet flow port and the sleeve flow port;
• maintaining a drilling fluid flow through the valve sleeve so that the first force is greater than the biasing spring force plus the second force;
• and
• decreasing the fluid flow through the valve sleeve so as to allow the biasing mechanism to shift the valve sleeve from an open position to the closed position.

A drill string flow control valve system comprising:

• a valve housing, wherein the valve housing is characterized by a tubular wall extending from a first end to a second end and defining a valve interior, wherein the valve housing has an internal housing flow path formed between said first and second ends with a housing outlet flow port disposed along said internal flow path;
• a valve sleeve disposed at least partially in the valve housing, the valve sleeve having a first end and a second end and characterized by a valve sleeve wall extending between said first and second ends, said valve sleeve having a sleeve flow port adjacent the first end, wherein the valve sleeve is axially movable within the valve housing between a closed position and an open position, such that fluid flow between said housing outlet flow port and said sleeve flow port is substantially impeded when the valve sleeve is in the closed position and wherein the sleeve flow port and the housing outlet flow port are substantially aligned when in the open position;
• wherein the valve sleeve has an upper pressure surface defined thereon so as to provide a first surface area upon which a first fluid pressure from the internal housing flow path may act to provide a downward force on the valve sleeve, and wherein the valve sleeve has a lower pressure surface defined thereon so as to provide a second surface area upon which a second fluid pressure may act to provide an upward force on the valve sleeve;
• a spring, wherein the spring biases the valve sleeve to the closed position by exertion of a biasing force on the valve sleeve;
• an upper pressure port disposed in said valve sleeve wall between said sleeve flow port and the second end of said valve sleeve, said upper pressure port in fluid communication with the upper pressure surface, said upper pressure port disposed to allow the first fluid pressure to act upon the upper pressure surface, wherein the first fluid pressure is measured from within said valve housing;
• a lower pressure port extending through the tubular wall of said valve housing so as to allow the second fluid pressure to act upon the lower pressure surface from external the valve housing;
• an elongated piston having a first end and a second end and axially movable within the valve housing, wherein the second end of the piston is disposed to bear against the valve sleeve and wherein the first end of the piston has a piston pressure surface characterized by a piston surface area;
• and
• a piston pressure port split off from said internal housing flow path that allows a fluid pressure internal to the valve to act upon the piston pressure surface.

A drill string flow control valve system comprising:

• a valve housing formed of a tubular member extending from a first end to a second end and characterized by an external surface, said tubular member having a first flow path internally disposed therein;
• a valve sleeve slidingly mounted in the valve housing;
• a piston having a first end and a second end and slidingly mounted in the valve housing between said first end of the tubular member and said valve sleeve, said wherein the second end of the piston is disposed to bear against the valve sleeve;
• a piston pressure port split off from said first internal housing flow path, said piston pressure port in fluid communication with the first end of said piston to allow a fluid pressure internal to the valve to act upon the first end of the piston;
• a biasing mechanism for biasing the valve sleeve against the piston;
• a first pressure port in the valve sleeve, said first pressure port split off from said internally disposed first flow path, said first pressure port in fluid communication with a first surface of the sleeve to provide a pressure acting on the first surface of the sleeve;
• and
• a second pressure port in fluid communication with a second surface of the sleeve to provide a pressure acting on the second surface of the sleeve, said second pressure port in fluid communication with the external surface of said valve housing.

A drill string flow control valve comprising:

• a valve housing wherein the valve housing has an internal housing flow path with a housing outlet flow port disposed along said flow path;
• a valve sleeve disposed at least partially in the valve housing, the valve sleeve having a sleeve flow port and a valve sleeve wall, wherein the valve sleeve is axially movable within the valve housing between a closed position and an open position, such that the valve sleeve wall substantially impedes fluid flow from the housing outlet flow port to the sleeve flow port when the valve sleeve is in the closed position and wherein the sleeve flow port and the housing outlet flow port are substantially aligned when in the open position;
• wherein the valve sleeve has an upper pressure surface defined thereon so as to provide a first surface area upon which a first fluid pressure from the housing flow path may act to provide a downward force on the valve sleeve and wherein the valve sleeve has a lower pressure surface defined thereon so as to provide a second surface area upon which a second fluid pressure external to the valve housing may act to provide an upward force on the valve sleeve;
• a spring, wherein the spring biases the valve sleeve to the closed position by exertion of a biasing force on the valve sleeve;
• an upper pressure port that allows the first fluid pressure to act upon the upper pressure surface;
• a lower pressure port that allows the second fluid pressure to act upon the lower pressure surface.

A method for preventing u-tubing in a drill string comprising:

• providing a valve housing, wherein the valve housing is characterized by a tubular wall extending from a first end to a second end and defining a valve interior, wherein the valve housing has an internal housing flow path formed between said first and second ends with a housing outlet flow port disposed along said internal flow path;
• providing a valve sleeve disposed at least partially in the valve housing, the valve sleeve having at least two pressure surfaces and axially movable within the valve housing between a closed position and an open position,
• providing a piston within the valve housing and bearing against the valve sleeve;
• biasing the valve sleeve under a biasing force in a first direction against the piston so as to close the valve;
• introducing drilling fluid into the valve housing to induce a fluid pressure therein;
• initiating fluid flow through the valve housing by causing said first fluid pressure to be applied to the piston pressure surface, thereby causing said piston to urge the valve sleeve in a second direction opposite the first direction;
• once fluid flow has been initiated, applying a fluid pressure from within the valve housing to a first surface of the valve sleeve to generate a first force to urge the valve sleeve in the second direction;
• once fluid flow has been initiated, applying a fluid pressure from external to the valve housing to a second surface of the valve sleeve to generate a second force to urge the valve sleeve in the first direction;
• maintaining a drilling fluid flow through the valve sleeve so that the first force is greater than the biasing spring force plus the second force;
• and
• decreasing the fluid flow through the valve sleeve so as to allow the biasing force to shift the valve sleeve in the first direction, thereby urging the valve into a closed position.